You have been warned
Alex Mustard (United Kingdom)
When Alex went diving in the Lembeh Strait in North Sulawesi, he was on a mission to celebrate the smaller sea creatures. Equipped with a new high-magnification lens, he encountered this variable neon nudibranch (sea slug) crawling across the seabed. Less than 2 centimetres (an inch) long, with green gills on its back and orange mouthparts, it has orange, feather-like rhinophores that it uses to ‘smell’ out its prey – sea squirts. It incorporates distasteful chemicals from the sea squirts’ skin into a slimy mucus and uses neon colours to warn predators that it tastes bad. Alex wanted an eye-level view of this unforgettable mollusc. But even with a small aperture, it was a challenge: there was little depth of field (amount in focus) and the subject was moving – and a slug’s pace under magnification is surprisingly fast.